Former environment minister Peter Garrett rejected a request that all power be cut to homes while insulation was being installed, less than three months before the fourth installer died.

The request was personally emailed to Mr Garrett from the father of the home insulation program's first victim Matthew Fuller, who was electrocuted while installing insulation in the ceiling of a Queensland home on October 14, 2009.

In his email, Kevin Fuller questioned why insulation installers were climbing into roof spaces without having all the power to a house switched off first.

"Why can't the legislators instruct that as a result of the risk assessment that must be done, if there is any doubt over the safety of installers, the property or the home owners - the electricity should be turned off or the job cannot be done,'' he said in the November 27 email.

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In bold text Mr Fuller wrote: "If in doubt turn the power off."

Mr Garrett told the royal commission investigating the former Labor federal government's failed insulation scheme on Wednesday he did not believe the mandate was necessary.

"I don't think mandating eliminates risk," Mr Garrett said.

He said installers were "advised" to turn off domestic power supply to the work area.

Mr Garrett said mandating that advice was not a proposal put to him by the Electrical Safety Office of Queensland.

"... had the Electrical Safety Office referenced the issue ... it would have come to me, but it didn't," he said.

Less than three months later, Matthew Sweeney, 22, was electrocuted laying insulation sheeting in the ceiling cavity of a home at Milla Milla in north Queensland on February 4, 2010.

Counsel Elizabeth Wilson asked Mr Garrett whether he had considered mandating turning off power, although it was not recommended by his department.

"Surely you're not limited to the recommendations of the department ... you're an intelligent man," Ms Wilson said.

Mr Garrett replied: "The department would provide to me any relevant information ..."

"It was not brought to me in terms of advice ... and I did not consider it."

Mr Garrett said he would make notes on briefs provided by his department if he required further information on an issue.

He said he did not make any notes about the mandating of switching power off on any briefs about the home insulation program.